Patterning of magnetic thin film using energized ions

ABSTRACT

A method for patterning a magnetic thin film on a substrate includes: providing a pattern about the magnetic thin film, with selective regions of the pattern permitting penetration of energized ions of one or more elements. Energized ions are generated with sufficient energy to penetrate selective regions and a portion of the magnetic thin film adjacent the selective regions. The substrate is placed to receive the energized ions. The portions of the magnetic thin film are rendered to exhibit a magnetic property different than selective other portions. A method for patterning a magnetic media with a magnetic thin film on both sides of the media is also disclosed.

RELATED APPLICATIONS

This application includes subject matter related to U.S. patentapplication Ser. No. 12/029,601 filed on Feb. 12, 2008 and entitled“Magnetic Domain Patterning Using Plasma Ion Implantation” which isincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to patterning of magnetic thinfilm, and more particularly to a method of patterning magnetic thin filmof a magnetic recording medium, using energized ions.

BACKGROUND

There is an ever present need for higher density information storagemedia for computers. Currently, the prevalent storage media is the harddisk drive (HDD). An HDD is a non-volatile storage device which storesdigitally encoded data on rapidly rotating disks with magnetic surfaces.The disks are circular, with a central hole. The disks are made from anon-magnetic material, usually glass or aluminum, and are coated on oneor both sides with magnetic thin films, such as cobalt-based alloy thinfilms. HDDs record data by magnetizing regions of the magnetic film withone of two particular orientations, allowing binary data storage in thefilm. The stored data is read by detecting the orientation of themagnetized regions of the film.

A typical HDD design consists of a spindle which holds one or moredisks, spaced sufficiently apart to allow read-write heads to access oneor both sides of one or more disks. The disks are fixed to the spindleby clamps inserted into the central holes in the disks. The disks arespun at very high speeds. Information is written onto and read off adisk as it rotates past the read-write heads. The heads move in veryclose proximity to the surface of the magnetic thin film. The read-writehead is used to detect and/or modify the magnetization of the materialimmediately underneath it. There is one head for each magnetic disksurface on the spindle. An arm moves the heads across the spinningdisks, allowing each head to access almost the entire surface of acorresponding disk.

In a conventional magnetic media, each bit cell includes a plurality ofmagnetic grains randomly dispersed. Ideally, the plurality of magneticgrains are physically separated from each other so as to provideimproved, write-ability, signal to noise ratio (SNR) and thermalstability.

As the aerial density of magnetic recording media increases, number ofbit cells per square inch increases. This reduces the size of the bitcell. To effectively measure a transition, a minimum number of magneticgrains are required in a bit cell. As the size of a bit cell reduces,the magnetic grain size has to be correspondingly reduced to provide aminimum number of magnetic grains in the bit cell. If isolation ofmagnetic grains and reduction in magnetic grain size are advanced toensure low noise, the recording density will be limited because ofthermal disturbances.

For improvement of a recording density, it is desirable to reduce arecording cell size on a media, which brings about reduction in signalmagnetic field intensity generated from the media. In order to meet theSNR required for a recording system, noise must be reduced correspondingto reduction in signal intensity. The media noise is mainly caused byfluctuation of a magnetization transition, and the fluctuation isproportional to a size of a magnetization reversal unit made of magneticgrains. Therefore, in order to reduce the media noise, it is required toisolate magnetic grains by disrupting exchange interaction betweenmagnetic grains.

Magnetic energy of a single isolated magnetic grain is given by aproduct of magnetic anisotropy energy density and volume of the grain.It is desirable to reduce the media thickness in order to reduce amagnetization transition width. It is also desirable to reduce the grainsize in order to meet a requirement for low noise. Reduced magneticgrain size significantly lowers the volume of magnetic grain, andfurther significantly lowers magnetic energy of the grain. If themagnetic energy of a given magnetic grain in a magnetic media is severalhundred times the thermal energy at an operating temperature (forexample, at room temperature), resistance against thermal disturbance isconsidered to be sufficient. However, if the magnetic energy of themagnetic grain is less than a hundred times the thermal energy, there isa possibility that the magnetization direction of the magnetic grain maybe reversed by thermal disturbance, potentially leading to loss ofrecorded information.

Various alternatives have been proposed to overcome the problem ofthermal disturbances. One alternative is to use a magnetic material withhigh magnetic anisotropy. These magnetic materials need higher recordingsaturation magnetic field from a head to write the magnetic media.Another alternative is to use thermally assisted recording, where ahighly anisotropic magnetic material is used and a recording portion isheated by light irradiation during recording. The heat lowers theanisotropy of magnetic grains and the recording saturation magneticfield. This permits writing of the magnetic media with conventionalmagnetic head.

As the aerial density increases, there are a minimum number of magneticgrains that are still required per bit cell and there is a limitation onhow small a magnetic grain can be practically achieved.

An alternate magnetic media that is being explored is a patterned media,where magnetic portions alternate with non-magnetic portions. Forexample, a bit patterned media may have magnetic portions defining amagnetic domain as islands surrounded by non-magnetic portions. A trackpatterned media may have for example, a concentric track of magneticportions separated by non-magnetic portions.

Various alternatives have been proposed to manufacture these media,however there still remains a need to come up with a method that is costeffective and compatible with high volume manufacturing. It is in thiscontext that the embodiments of this disclosure arise.

SUMMARY OF THE INVENTION

The concepts and methods of this disclosure allow for high volumemanufacturing of magnetic media with some portions of the magnetic thinfilm rendered to exhibit a magnetic property different than otherportions of the magnetic thin film.

In one aspect, the present disclosure is a method of patterning amagnetic thin film on a substrate. The method includes providing apattern about the magnetic thin film, with selective regions of thepattern permitting penetration of energized ions of one or more elementsthrough and impinges upon portions of the magnetic thin film. Energizedions of one or more elements are generated with sufficient energy topenetrate selective regions of the pattern and a portion of the magneticthin film adjacent the selective regions. The substrate is placed toreceive the energized ions. The portions of the magnetic thin filmadjacent the selective regions are rendered to exhibit a magneticproperty different than selective other portions of the magnetic thinfilm.

In another aspect, the present disclosure is a method for patterning amagnetic media having two sides with a magnetic thin film on both sides.The method includes, providing a pattern about the magnetic thin film onboth sides of the magnetic media, with selective regions of the patternpermitting penetration of energized ions of one or more elements throughand impinge upon portions of the magnetic thin film. Energized ions ofone or more elements are generated with sufficient energy to penetrateselective regions of the pattern and a portion of the magnetic thin filmadjacent the selective regions on both sides of the magnetic media. Themagnetic media is placed to receive energized ions. The portions of themagnetic thin film adjacent the selective regions on both sides of themagnetic media are rendered to exhibit a magnetic property differentthan selective other portions of the magnetic thin film.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects and features of the present invention willbecome apparent to those ordinarily skilled in the art upon review ofthe following description of specific embodiments of the invention inconjunction with the accompanying figures, wherein:

FIG. 1 is process flow chart of an exemplary method of this disclosure;

FIG. 2 is a partial plan view of an exemplary mask for use about themagnetic thin film, as a pattern;

FIG. 3 is an exemplary resist with a pattern disposed about the magneticthin film;

FIG. 4 is a schematic of a process chamber for use with this disclosure,showing a first disk holder apparatus of this disclosure;

FIG. 5 is a cross-sectional representation of a pattern about themagnetic thin film;

FIG. 6 is a cross-sectional representation of the magnetic thin film,after ion penetration;

FIGS. 7A and 7B show Helium ion penetration profile through the resistand the magnetic thin film;

FIG. 7C shows magnetization curve for portion of the magnetic film notsubjected to Helium ion implantation;

FIG. 7D shows magnetization curve for portion of the magnetic filmsubjected to Helium ion implantation;

FIGS. 8A and 8B show Boron ion penetration profile through the resistand the magnetic thin film;

FIG. 8C shows concentration of Boron and Cobalt ions in the magneticthin film, after Boron ion implantation;

FIG. 8D shows magnetization curve for portion of the magnetic film notsubjected to Boron ion implantation;

FIG. 8E shows magnetization curve for portion of the magnetic filmsubjected to Helium ion implantation;

FIG. 9A shows Silicon ion penetration profile through the magnetic thinfilm; and

FIG. 9B shows depth profile of Silicon ions in the magnetic thin film,after Silicon ion implantation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present disclosure will now be described in detail with reference tothe drawings, which are provided as illustrative examples of thedisclosure so as to enable those skilled in the art to practice thedisclosure. Notably, the figures and examples below are not meant tolimit the scope of the present disclosure to a single embodiment, butother embodiments are possible by way of interchange of some or all ofthe described or illustrated elements. Moreover, where certain elementsof the present disclosure can be partially or fully implemented usingknown components, only those portions of such known components that arenecessary for an understanding of the present disclosure will bedescribed, and detailed descriptions of other portions of such knowncomponents will be omitted so as not to obscure the disclosure. In thepresent specification, an embodiment showing a singular component shouldnot be considered limiting; rather, the disclosure is intended toencompass other embodiments including a plurality of the same component,and vice-versa, unless explicitly stated otherwise herein. Moreover,applicants do not intend for any term in the specification or claims tobe ascribed an uncommon or special meaning unless explicitly set forthas such. Further, the present disclosure encompasses present and futureknown equivalents to the known components referred to herein by way ofillustration.

In general, the present disclosure contemplates providing a pattern withselective regions permitting penetration of ions of one or more elementsthrough and impinges upon portions of a magnetic thin film. Energizedions of one or more elements are generated with sufficient energy topenetrate selective regions of the pattern and a portion of the magneticthin film adjacent the selective region. The substrate is placed toreceive the energized ions. Portions of the magnetic thin film adjacentthe selective regions are rendered to exhibit magnetic propertydifferent than other portions of the magnetic thin film. This method isapplicable to hard disk drive fabrication, allowing very high aerialdensity information storage.

An exemplary method of the current disclosure is shown in FIG. 1. Themethod for patterning a magnetic thin film on a substrate includes thefollowing steps: (1) providing a pattern about the magnetic thin film,with selective regions permitting penetration of energized ions of oneor more elements; (2) generating energized ions of one or more elementswith sufficient energy to penetrate selective regions of the pattern anda portion of the magnetic thin film adjacent the selective regions; (3)placing the substrate to receive the energized ions; and (4) renderingportions of the magnetic thin film adjacent the selective regions toexhibit a magnetic property different than selective other portions ofthe magnetic thin film.

In one embodiment, a mask that is not conducive to the penetration ofenergized ions through with selective regions that permit thepenetration of ions through may be used as a pattern. FIG. 2 showspartial plan view of an exemplary mask 200 for use about the magneticthin film as a pattern. For example, the mask 200 may be made ofpolymeric material, for example, polyvinyl alcohol (PVA) material withportions 202 not conducive to the penetration of energized ions throughand selective regions 204 that are conducive to the penetration ofenergized ions through. An exemplary method to create PVA templates isdescribed by Schaper in U.S. Pat. No. 6,849,558, which is incorporatedby reference herein. The teachings of Schaper may be adapted to createthe mask 200 with portions 202 not conducive to the penetration ofenergized ions through and selective regions 204 that are conducive tothe penetration of energized ions through. For example, the thickness ofthe portions 202 may be chosen such that the energized ions do notpenetrate completely through the portions 202. Although portions 202have been shown to be round, as one skilled in the art appreciates, theshape and location of portions 202 may be beneficially chosen. Forexample, the shape of portions 202 may be oval, square, rectangular orany other shape depending upon the needs of the application.

In yet another embodiment, a resist may be coated over the magnetic thinfilm and a pattern created in the resist, for example, using nanoimprintlithography. There are two well known types of nanoimprint lithographythat are applicable to the present disclosure. The first isthermoplastic nanoimprint lithography [T-NIL], which includes thefollowing steps: (1) coat the substrate with a thermoplastic polymerresist; (2) bring a mold with the desired three-dimensional pattern incontact with the resist and apply a prescribed pressure; (3) heat theresist above its glass transition temperature; (4) when the resist goesabove its glass transition temperature the mold is pressed into theresist; (5) cool the resist and separate the mold from the resist,leaving the desired three-dimensional pattern in the resist.

The second type of nanoimprint lithography is photo nanoimprintlithography [P-NIL], which includes the following steps: (1) aphoto-curable liquid resist is applied to the substrate; (2) atransparent mold, with the desired three-dimensional pattern, is pressedinto the liquid resist until the mold makes contact with the substrate;(3) the liquid resist is cured in ultraviolet light, to turn the liquidresist into a solid; (4) the mold is separated from the resist, leavingthe desired three-dimensional pattern in the resist. In P-NIL the moldis made of a transparent material such as fused silica.

FIG. 3 shows a cross-sectional representation of an exemplary pattern300 after nanoimprint lithography. The patterned resist 310 on magneticthin film 320 on substrate 330 is shown having a depression 340 withselective regions 350 where the resist has been substantially displaced.However, the selective regions 350 have a small amount of resist leftcovering the surface of the magnetic thin film 320. This is typical fora nanoimprint process. When using a resist pattern as a mask for ionimplantation, it is not necessary for the entire resist layer to beremoved in the areas where the implant species will be implanted.However, the remaining layer should be thin enough not to cause asubstantial barrier for the implant species to penetrate through.Furthermore, the contrast between the areas with thick resist and thinremaining resist should be large enough so the resist in the areas thathave the thick resist is capable of stopping the ion species before theyreach the magnetic thin film. Alternatively, the thin remaining resistin selective regions 350 can be removed with an isotropic resist removalprocess such as a descum process or a slight ash process or any otherappropriate technique.

In nanoimprint lithography, as the imprint process displaces resist toform selective regions 350, there is a need to control the amount ofresist that is displaced when a mold having a plurality of projectionscorresponding to the depression 340 is brought in contact with theresist and pressure is applied. Typically, the width w of the depression340 may be about the same dimension as the depth d of the depression 340and the height h of the resist is at least as high as the depth d of thedepression 340, in order to control the amount of resist that isdisplaced during the stamping process. If the depth d of the depression340 is substantially higher than the width w of the depression 340, theamount of resist that is displaced may be so high it may be impracticalto precisely transfer the pattern from a mold to the resist 310.

The nanoimprint lithography process can be implemented using a full disknanoimprint scheme, where the mold is large enough to imprint one entiresurface. Alternatively, a step and repeat imprint process can be used.In a preferred embodiment, a full disk scheme is used. The nanoimprintprocess can also be performed with both sides at once. For example, thedisk may first be coated with a resist layer on both sides. Then thedisk goes into a press where molds are pressed against both sides of thedisk to imprint the desired pattern on both sides of the disksimultaneously.

Conventional photolithographic processes may also be used, in which casephotoresist is spun on the disks, followed by exposure of the resistthrough a mask, and development of the exposed resist.

After the patterning, the disks have a pattern of resist with selectiveregions 350 of the pattern permitting penetration of energized ionsthrough and impinge upon portions of the magnetic thin film 320 adjacentthe selective regions 350. Portions of the resist other than theselective regions 350, for example, portion 360 have sufficientthickness to prevent the penetration of energized ions through, therebypreventing the energized ions to impinge upon the magnetic thin film.

If a mask 200 is used instead, the mask 200 is placed adjacent themagnetic thin film and selective regions 204 of the mask 200 will permitthe penetration of energized ions through the mask and impinge uponportions of the magnetic thin film adjacent the selective regions 204.In one embodiment, the mask 200 is positioned proximate the magneticthin film. In another embodiment, the mask 200 is positioned in contactwith the magnetic thin film or magnetic thin film covered with acoating. The coating may be conducive to the adhesion of the mask. Thecoating may also act as a protective coating over the magnetic thinfilm. The coating may be a carbon layer acting as a protective coatingover the magnetic thin film.

Now referring back to FIG. 1, in step 104, energized ions of one or moreelements are generated with sufficient energy to penetrate selectiveregions of the pattern and impinge upon portions of the magnetic thinfilm adjacent the selective regions. In one embodiment, a vacuum chamberis provided and one or more gases containing compounds of one or moreelements are injected. A plasma is ignited by using high voltage andenergized ions of one or more elements are released.

In step 106, the substrate is placed to receive the energized ions. Inone embodiment, the substrate is placed in a vacuum chamber whereenergized ions of one or more elements are generated. In one embodiment,the substrate is placed in a plasma containing one or more energizedions. In one embodiment, the substrate is biased to attract theenergized ions. If a mask 200 is used, the energized ions pass throughthe selective regions 204 of the mask 200 and impinge upon portions ofthe magnetic thin film adjacent the selective regions 204. If a resist310 is used as a pattern, the energized ions pass through the selectiveregions 350 and impinge upon portions of the magnetic thin film adjacentthe selective regions 350. In one embodiment, the energized ionspenetrate into portions of the magnetic thin film adjacent the selectiveregions 350. In one embodiment, the energized ions partially penetrateinto portions of the magnetic film adjacent the selective regions 350.In one embodiment, the energized ions substantially penetrate intoportions of the magnetic thin film adjacent the selective regions 350.

In one embodiment, plasma ion implantation may be used to provide highimplant doses at low energies. Since the sputtered magnetic thin filmsare typically only tens of nanometers thick the low ion energies areeffective and the high dose provides high throughput. Furthermore, as isclear from FIG. 4, plasma ion implantation of both sides of the diskscan be carried out at the same time. Although a double side plasma ionimplant is preferred, a single side plasma ion implant can be usedwithout departing from the spirit of the disclosure. In the single sideplasma ion implant a first side will be implanted, then the disk will beflipped over and the second side will be implanted.

A plasma ion implantation tool 400 configured for handling disks, forexample, a substrate with a magnetic thin film, with a pattern about themagnetic thin film, with selective regions of the pattern permittingpenetration of energized ions of one or more elements through andimpinge upon portions of the magnetic thin film is shown in FIG. 4.

Referring to FIG. 4, a chamber 410 is maintained under vacuum by vacuumpump 420. Gas supply 430 is connected by pipe 432 and valve 435 to thechamber 410. More than one gas may be supplied through valve 435 andmultiple gas supplies and valves may be used. For example, dopant gasescontaining one or more species elements may be supplied to the chamber410. A rod 440 holds disks 450. A radio frequency (RF) power supply 460is connected between the rod 440 and the wall of the chamber 410. Thewall of the chamber 410 is connected to an electrical earth. In additionto the RF power supply an impedance matching device and a power supplyfor applying a direct current (DC) bias may be included. The rod 440 maybe coated with graphite or silicon to protect it from the plasma.Furthermore, the rod and its surface are highly conductive to facilitatea good electrical contact between the rod and the disks. The disks 450can be fixed in place using clamps 455 or other means; the clamps 455will not only fix the disks 450 in place but also ensure a goodelectrical connection between the disks 450 and the rod 440. The rod isconfigured to carry many disks (only three disks 450 are shown for easeof illustration). Furthermore, the chamber 410 can be configured to holdmany rods loaded with disks for simultaneous plasma ion implantation.The rods 440 are readily moved in and out of the chamber 410.

Processing of the disks in the plasma ion implantation tool 400 proceedsas follows. One or more of the disks 450 are loaded onto the rod 440.The rod 440 is loaded into the chamber 410. The vacuum pump 420 operatesto achieve a desired chamber pressure. A desired gas containing implantspecies is leaked into the chamber from gas supply 430 through valve 435until a desired operating pressure is reached. The RF power supply 460is operated so as to ignite a plasma which surrounds the surfaces of oneor more of the disks 450. The DC power supply can be used to control theenergy of ions that are implanted into the magnetic thin film. RFbiasing may also be used.

Ions that can be readily implanted from a plasma and that will beeffective in modifying the magnetic properties of a typical sputteredmagnetic thin films, such as Co—Pt and Co—Pd, are: hydrogen, helium,boron, sulfur, aluminum, lithium, neon and germanium and combinations ofthese elements. This list is not intended to be exhaustive. Any ionreadily formed in a plasma and effective in modifying the magneticproperty of a magnetic thin film will suffice. Ideally, the ion that canchange magnetic property of the magnetic thin film into thermally stableless magnetic or more magnetic areas at the lowest dose will bepreferred.

Further details of plasma ion implantation chambers and process methodsare available in U.S. Pat. Nos. 7,288,491 and 7,291,545 to Collins etal., incorporated by reference herein. The primary difference betweenthe chamber of the present disclosure and the chamber of Collins et al.is the different configuration for holding the substrates. The diskholders of the present disclosure allow implantation of both sides atonce, whereas the substrates in Collins et al. sit on a wafer chuckduring processing. Those skilled in the art will appreciate how theplasma ion implantation tools and methods of Collins et al. can beutilized in the present disclosure.

After placing the substrate to receive energized ions in step 106, theportions of the magnetic thin film adjacent the selective regions arerendered to exhibit a magnetic property different than selective otherregions as illustrated in step 108. In one embodiment, the energizedions that penetrate into portions of the magnetic thin film adjacent theselective regions 350 render the portions of the magnetic thin filmadjacent the selective regions to exhibit a magnetic property differentthan selective other regions. The process may additionally include aresist strip step, if a resist is used as a pattern. The resist stripstep can be facilitated by a conventional descum and ash operation inthe plasma ion implantation chamber prior to removing the disks. Theresist strip step may be a wet chemical process that is well known inthe art.

If a mask 200, for example, a PVA mask is used, the process mayadditionally include removal of the mask 200. In one embodiment, the PVAmask may be removed using a process to dissolve the PVA mask 200, forexample, using an aqueous solution. In some embodiments, non-aqueoussolution may be used.

The energy of ions available from a plasma implantation process is inthe range of about 100 eV to about 15 keV. However, for implanting intothe magnetic thin films, which are tens of nanometers thick, thedesirable energy range is between about 1 keV to about 1 keV. The energyrange that is selected is based upon the element chosen, the resistthickness, resist ion stopping capability and the desired magneticproperties. For example, bias voltages of about 1 kV to 11 kV may beused to generate desirable energy range.

FIG. 5 is a cross-sectional representation of a pattern 510 disposedabout the magnetic thin film 520, with arrows 530 representing generaldirection of bombardment of energized ions. The energized ions penetratethrough selective regions 540 of the resist 510 and penetrate a portion550 of the magnetic thin film 520, adjacent the selective regions 540.

FIG. 6 is a cross-sectional representation of the magnetic thin film 520after ion implantation, with portions 550 subjected to ion implantation.The portions 550 of the magnetic thin film 520 are rendered to exhibit amagnetic property different than selective other portions 560 of themagnetic thin film 520.

Following examples are provided to illustrate various applications ofion implantation to achieve desired magnetic properties.

EXAMPLES

Experiments were conducted to determine ion stopping properties ofresist for Helium and Boron ions for a given bias voltage.

Helium ion implant: Experiments were conducted for Helium ionimplantation at 7 kV and 2 kV bias voltages. At 7 kV, the resistthickness required to stop the penetration of the Helium ions throughthe resist layer was about 120 nm. The resist thickness at the selectiveregions of the pattern can be as high as 45 nm and still provide apenetration of Helium ions through a 20 nm thick Co-based magnetic thinfilm adjacent the selective regions of the pattern. At 2 kV, the resistthickness required to stop the penetration of the Helium ions throughthe resist layer was about 85 nm. The resist thickness at the selectiveregions of the pattern can be as high as 10 nm and still provide apenetration of Helium ions through a 20 nm thick Co-based magnetic thinfilm adjacent the selective regions of the pattern.

Boron ion implant: Experiment was conducted for Boron ion implantationat 9 kV bias voltage. At 9 kV, the resist thickness required to stop thepenetration of the Boron ions through the resist layer was about 65 nm.The resist thickness at the selective regions of the pattern can be ashigh as 10 nm and still provide a penetration of Boron ions through a 20nm thick Co-based magnetic thin film adjacent the selective regions ofthe pattern.

Magnetic Properties Example 1

A glass substrate sputtered with a FeNi alloy soft under layer of about100 nm was used. About 20 nm magnetic thin film layer of CoCrPt alloywas sputtered on the FeNi alloy soft under layer. The prepared sample asdescribed above was subjected to a plasma containing He ions, byinjecting dopant gas Helium into the process chamber. The processchamber pressure was about 15 mtorr, the RF bias voltage was about 2 kV,the source power was about 500 watts, the dopant gas Helium was injectedat a flow rate of about 300 sccm and the implant time was about 25seconds. Optionally, an inert gas may also be injected to assist in thecreation of plasma. For example, Argon at a flow rate of about 16 sccmmay also be injected.

The penetration of the He ions into the sample was profiled using asimulation program with process parameters described above. A simulationprogram known as TRIM may be used to perform the simulation. TRIMprogram is available as part of a group of programs known as SRIM fromwww.srim.org. FIGS. 7A and 7B show the results of simulation. Nowreferring to FIG. 7A, it is apparent that about 85 nm thick resist willbe sufficient to stop energized He ions from penetrating into the CoCrPtmagnetic thin film layer. Now, referring to FIG. 7B, it is apparent thatabout 10 nm of resist layer and about 28 Angstroms of Carbon layer willbe successfully penetrated by energized ions and further penetratesubstantially through the CoCrPt magnetic thin film layer of about 20nm.

The magnetic properties of the magnetic film for a sample that was notsubjected to He ion implantation was measured using Physical PropertyMeasurement System, to establish a base line. After subjecting thesample to He ion implantation, the magnetic properties of portions ofthe magnetic film subjected to He ion implantation was measured usingPhysical Property Measurement System. FIG. 7C shows the magnetizationcurve for magnetic film not subjected to He ion implantation. It isevident from FIG. 7C, the saturation magnetism (Ms) is about 1.36 tesla.FIG. 7D shows the magnetization curve for portions of the magnetic filmsubjected to He ion implantation. It is evident from FIG. 7D, thesaturation magnetism (Ms) for the portion of magnetic film subjected toHe ion implantation has dropped to about 0.1 tesla, as compared to baseline magnetic thin film not subjected to He ion implantation. Therefore,a magnetic thin film may be subjected to He ion implantation underappropriate process conditions to substantially change the magneticproperty to a state where the selective portion exhibits significantlydifferent magnetic property. Although the experiment was conducted at abias voltage of about 2 kV, the bias voltage may be in the range of 1 kVto 11 kV and preferably in the range of 1 kV to 3 kV.

Example 2

Similar sample as used in Example 1 was used for penetration of Boronions. The prepared sample as described above, was subjected to a plasmacontaining Boron ions, by injecting dopant gas BF₃ into the processchamber. The process chamber pressure was maintained at about 15 mtorr,the RF bias voltage was about 9 kV, the source power was about 500watts, the dopant gas BF₃ was injected at a flow rate of about 300 sccmand the implant time was about 20 seconds. Optionally, an inert gas mayalso be injected to assist in the creation of plasma. For example, Argonat a flow rate of about 16 sccm may also be injected.

The penetration of the Boron ions into the sample was profiled using asimulation program with process parameters described above. FIGS. 8A and8B show the results of the simulation. Now referring to FIG. 8A, it isapparent that a 65 nm thick resist will be sufficient to stop energizedBoron ions from penetrating into the CoCrPt magnetic thin film layer. Itis evident from FIG. 8A that about 10 nm of resist layer and about 28Angstroms of Carbon layer can be successfully penetrated by energizedions. The energized ions can further penetrate substantially through theCoCrPt magnetic thin film layer of about 20 nm.

Referring to FIG. 8C, concentration of Boron and Co atoms weredetermined using Secondary Ion Mass Spectroscope (SIMS). From FIG. 8C,it is evident that Co concentration remained substantially unchanged. Itis also evident that Boron concentration remained constant for about 10nm deep and gradually decreased thereafter.

The magnetic properties of the magnetic film for a sample that was notsubjected to Boron ion implantation was measured using Physical PropertyMeasurement System, to establish a base line. After subjecting thesample to Boron ion implantation, the magnetic film subjected to Boronion implantation was measured using Physical Property MeasurementSystem. FIG. 8D shows the magnetization curve for the magnetic film notsubjected to Boron ion implantation. As it is apparent from FIG. 8D, thesaturation magnetism (Ms) is about 1.36 tesla. FIG. 8E shows themagnetization curve for portions of the magnetic film subjected to Boronion implantation. As it is apparent from FIG. 8E, the saturationmagnetism (Ms) for the portion of magnetic film subjected to Boron ionimplantation has dropped to about 0.5 tesla, as compared to magneticthin film not subjected to Boron ion implantation. The Boron ionimplantation under these experimental conditions reduced themagnetization by about 50%.

Therefore, a magnetic thin film may be subjected to Boron ionimplantation under certain process conditions to change the magneticproperty of the selective portions so as to exhibit different magneticproperty. For example, the magnetic property of selective portions maybe changed to exhibit less magnetic property than portions not subjectedto Boron ion implantation. Although the experiment was conducted at abias voltage of about 9 kV, the bias voltage may be in the range of 1 kVto 11 kV and preferably in the range of 7 kV to 11 kV.

Example 3

Silicon substrate sputtered with about 20 nm of Co alloy layer wasprepared as samples for this example. The prepared sample was subjectedto a plasma containing Silicon ions, by injecting dopant gas SiH₄ intothe process chamber. The process chamber pressure was about 30 mtorr,the RF bias voltage was about 9 kV, the source power was about 500watts, the dopant gas SiH₄ was injected at a flow rate of about 75 sccmand the implant time was about 20 seconds.

The penetration of the Silicon ions into the sample was profiled using asimulation program with process parameters as described above. FIG. 9Ashow the results of the simulation. Now referring to FIG. 9A, it isevident that Si penetrates about 5-6 nm deep, with some tail up to 10 nmdeep.

After subjecting the sample to Silicon ion implantation, the depthprofile of the Si implant in the 20 nm Co film was measured using SIMS.FIG. 9B shows the depth profile for the Si implant. It is evident fromFIG. 9B that Si ions penetrated about 5-6 nm deep. It is noteworthy thatSi ion penetration depth profiled using the simulation programcorrelates well with the actual measurement of the Si penetration depth.

It is evident from the above examples that the resist thickness neededto stop penetration of energized ions through the resist layer andimpinge upon the magnetic thin film is dependent upon the elementspecies being used, the process parameters and the desired penetrationdepth of the ions into the magnetic thin film adjacent the selectiveregions of the resist layer that permits the penetration of chargedions. As the dimension of the selective regions of the resist layerpermitting the penetration of charged ions becomes small, there is aneed to reduce the resist thickness, so as to permit effectivenanolithography process during the pattern creation. As the resistthickness decreases, the resist layer may no longer be able to stoppenetration of energized ions in regions other than the selectiveregions.

One way to overcome this problem is to add a dopant to the resist thatincreases the resistance to the penetration of the charged ions. Forexample, the resist may be doped with a silicon containing compound toincrease the resistance to the penetration of charged ions through theresist. Other dopants that may be used to increase the resistance to thepenetration of the charged ions include compounds containing sulfur andphosphorus. In one embodiment, nano particles can be added as additivesto tune the resistance to the penetration of the charged ions. Forexample, nano particles of Aluminum oxide (Al₂O₃), Silicon dioxide(SiO₂), Ceria (CeO₂) and Titanium dioxide (TiO₂) may be used to tune theresistance to the penetration of the charged ions.

It is evident from the above examples that different element specieshave different effects on the magnetic properties based upon the processparameters and the desired penetration depth of the ions into themagnetic thin film. For example, one or more elements may beadvantageously used to modify the magnetic properties of the magneticfilm. As an example, a combination of Helium and Boron may provide addedbenefit. For example, Helium with less molecular weight can penetratedeeper into the magnetic thin film and change the magnetic properties,using less bias voltage. Boron with a higher molecular weight may beused either before or after the penetration of Helium to further impactthe magnetic properties of the magnetic thin film and also to act as abarrier for the Helium ions from escaping from the magnetic thin film,over time.

Although the combination of Helium and Boron has been described, oneskilled in the art appreciates that various other permutation andcombinations of elements may be used in sequence or together, to derivemagnetic and other properties that are favorable to the retention andenhancement of the modifications of the magnetic properties.

It is also evident from the above examples that different elementspecies may be used to modify the magnetic properties of the magneticthin film. For example, a compound containing elements that increase themagnetic property of the thin film upon ion implantation may be used.For example, platinum ion implantation may increase the magneticproperties of the magnetic thin film.

The present disclosure may be used for various types of magneticrecording media. For, example, the teachings of this present disclosuremay be used with recording media having a granular magnetic structure.The present disclosure may also be used for magnetic thin films that aremulti-layered. The magnetic thin film may also be a continuous magneticfilm and may be used with patterned media. The patterned media may bebit patterned media or track patterned media. In one embodiment, themagnetic thin film may be made of highly anisotropic magnetic material,suitable for a thermally assisted magnetic recording.

The present disclosure allows for very short process times. For example,it can take about ten seconds to implant the disks. Input and outputvacuum loadlocks will enable rapid transfer of disks in and out of thechamber and avoid losing time for pumpdown, thus allowing for very highthroughput. Those skilled in the art will appreciate how automatedtransfer systems, robotics and loadlock systems can be integrated withthe plasma ion implantation apparatus of the present disclosure.

The present disclosure in certain embodiments provides a method toselectively modify the magnetic properties of portions of magnetic thinfilm of a magnetic media. The selective modifications can beadvantageously used to increase one or more of the desirable propertieslike aerial density, write-ability, SNR and thermal stability of themagnetic media.

Although the present disclosure has been particularly described withreference to the preferred embodiments thereof, it should be readilyapparent to those of ordinary skill in the art that changes andmodifications in the form and details may be made without departing fromthe spirit and scope of the disclosure. It is intended that the appendedclaims encompass such changes and modifications.

What is claimed is:
 1. A method, comprising: disposing a pattern on amagnetic thin film on both sides of a substrate, with selective regionsof the pattern permitting energized ions of one or more elements topenetrate through the selective regions of the pattern and impinge uponportions of the magnetic thin film; positioning the substrate having thepattern thereon within a chamber; sequentially injecting helium and aboron-containing gas into the chamber, wherein the helium and theboron-containing gas are sequentially ionized into plasma to implantenergized helium and boron ions into the portions of the magnetic thinfilm adjacent the selective regions of the pattern disposed on thesubstrate, and wherein the energized helium ions and the energized boronions are implanted at the same bias voltage and the helium ions areimplanted within the magnetic thin film to a greater depth than theboron ions; and rendering the portions of the magnetic thin filmadjacent the selective regions on both sides of the substrate to exhibita magnetic property different than selective other portions of themagnetic thin film.
 2. The method of claim 1, wherein disposing thepattern includes coating a resist over the magnetic thin film andimprinting with a mold having a plurality of projections aligned withthe selective regions of the pattern.
 3. A method, comprising: disposinga magnetic thin film on a substrate; disposing a pattern on the magneticthin film, the pattern having selective regions which permit penetrationof energized ions; positioning the substrate having the pattern thereonwithin a chamber; sequentially injecting helium and a boron-containinggas into the chamber, wherein the helium and the boron-containing gasare sequentially ionized into plasma to implant energized helium andboron ions into portions of the magnetic thin film adjacent theselective regions of the pattern disposed over the substrate, andwherein the energized helium ions and the energized boron ions areimplanted at the same bias voltage and the helium ions are implantedwithin the magnetic thin film to a greater depth than the boron ions,and further wherein the bias voltage is within a range from about 1 kVto about 11 kV; and rendering the portions of the magnetic thin filmadjacent the selective regions to exhibit a magnetic property differentthan selective other portions of the magnetic thin film.
 4. The methodof claim 3, wherein disposing the pattern includes positioning a mask onthe magnetic thin film.
 5. The method of claim 4, wherein the maskcomprises polyvinyl alcohol.
 6. The method of claim 3, wherein thedisposing a pattern comprises: depositing a resist on a surface of themagnetic thin film; and contacting the resist with a mold having athree-dimensional pattern to create depressions in the resist, thedepressions creating areas of thin resist and areas of thick resist,wherein implanting the energized boron ions and the energized heliumions into the portions of the magnetic thin film adjacent the selectiveregions of the pattern comprises exposing the magnetic thin film to theplasma, wherein the energized helium ions and the energized boron ionshave sufficient energy to penetrate the thin resist to contact themagnetic thin film, but insufficient energy to penetrate the thickresist.
 7. The method of claim 6, further comprising removing theresist.
 8. The method of claim 6, wherein the resist is deposited andcured on the surface of the magnetic film using photo nanoimprintlithography.
 9. The method of claim 6, wherein the disposing a patternon the magnetic thin film comprises disposing a pattern on both sides ofthe substrate.